Prior art fiber optic connectors are known in which the optical fiber end to be connected is held in a guiding sleeve which can be shifted in a transverse direction by means of a bolt in one wall of the connector. One disadvantage of such prior art connectors is that alignment of the ends of the optical fibers being connected to those of a mating connector requires a manual mechanical adjustment. Another fault of the prior art is that the ends of the optical fibers are unprotected when the two mating connector parts are disconnected. The present invention overcomes these deficiencies in the prior art by providing means by which an automatic adjustment of the alignment of the ends of the optical fibers is made possible, and other means by which the ends of the optical fibers are protected against fouling and damage when the two mating connectors are separated.